Justin continued to present himself as a philosopher after his conversion to Christianity, and to see himself as engaged in a common pursuit with other philosophers. This is evident in the audacity of his addressing himself to the emperor and his adopted sons, Marcus Aurelius and Lucius, in the First Apology. There are only a few passages in Justin's works that contain a sustained discussion of philosophical topics. The most important of these is in the opening chapters of the Dialogue with Trypho where, after a brief initial discussion with Trypho about philosophy, Justin outlines his own philosophical education, and his encounter with 'an old man' who engages him in a dialogue about philosophy, a dialogue which is considerably more Socratic in tone than the Dialogue with Trypho itself. The Apologies contain discussions on fate and free will, and on the relationship between the teachings of philosophers such as Socrates and Christianity. The existence of God is axiomatic for Justin.